SEATAC, Wash. -- Residents who live near Sea-Tac Airport's newest runway are filing a class-action lawsuit against the Port of Seattle, claiming the noise and vibrations from low-flying planes have far surpassed what was promised by the Port of Seattle.

The suit claims when the runway was being built, the port stated it was only to be used as an alternate runway to reduce delays in bad weather. But last fall, port officials made public statements indicating that the third runway was always intended to be used at high-traffic times 365 days a year, the plaintiffs allege.

And since the runway's opening, lawyers for the plaintiffs say the port is now using the new runway for both departures and arrivals, and at all hours of the day. Part of that is due to ongoing construction on one of the airport's other runways that is supposed to last through the summer.

But lawyers point to a statement on the Port of Seattle's Web site, which says the FAA has made it clear it will not restrict the use of the third runway.

When the runway first opened, the port's Web site stated, "in general, the third runway won't be needed as often in good weather." That line no longer appears on the site.

"If you look at the record over the last 15 years, you'll see that the Port of Seattle says whatever it has to say to get the third runway operating. And that's true today," said Darrell Cochran, the plaintiffs' attorney.

Miriam Bearse, one of three plaintiffs in the case, claims the port used lies of limited use to sell the public on the third runway.

"It's not just the lies; it's also to have some sort of compensation and recognition of the impact on our property values on our homes," said Miriam Bearse, one of three plaintiffs in the case.

At issue is the word "primary." If indeed the third runway is a primary runway, area residents why their home weren't bought out like the other homes under the other two runways. A park now sits under the flight path of the other two runways.

"We knew, knew it was coming. We didn't think it was going to be like this," said Janelle Dempsey, another plaintiff who lives under the flight path.

The suit seeks damages for lowered property value and wants to prohibit planes from using the third runway on weekends and between 10 p.m. and 9 a.m. on week nights.

Plaintiffs also want to restrict planes from flying lower than 1,500 feet above the plaintiffs' homes and only allow no more than one plane to fly over their home per hour.

Port of Seattle officials told KOMO News they had not seen the lawsuit yet and would not comment on the case. But they did provide a link to statistics that show just how much the third runway is being used.